Mutagenicity of airborne particles.

The mutagenicity of airborne particles was studied in the Ames Salmonella system. The mutagenic activity of benzene extracts from airborne particles was more active in strain TA98 in the presence and absence of S9 mix than in strain TA100. The presence of mutagens, other than benzo[a]pyrene (B[a]P), which did not require S9 mix, was indicated. However, the monthly variation of direct-acting mutagenic activity showed a pattern similar to that of B[a]P at atmospheric concentration. The monthly variations of atmospheric NO, NO2, NO-2 and NO-3 concentrations were also similar to that of the direct-acting mutagenic activity. Atmospheric concentrations of heavy metals such as Pb, Zn, Cd, V and Cu were also found to be related to direct-acting mutagenic activity. These results suggest that emissions from automobiles, home heaters and power plants etc. may be a primary source of atmospheric, direct-acting mutagens. It is suggested that secondary direct-acting mutagens might be partly formed by the nitration of polycyclic aromatic hydrocarbons (PAH) with NO2 in the atmosphere because concentrations of B[a]P, NO2 and NO-3 increased simultaneously when the highest direct-acting mutagenic activity was observed.